Fingerprint sensor

Abstract

A fingerprint sensor includes: a panel including a sensor array including first electrodes extended in a first direction and second electrodes extended in a second direction intersecting with the first direction; and a forged fingerprint analyzer configured to provide signals having different frequencies to a first electrode group and a second electrode group, and to measure an impedance between the first electrode group and the second electrode group to determine whether a fingerprint applied to the sensor array is forged, wherein the first electrode group includes a portion of a plurality of electrodes among the first electrodes or the second electrodes, and the second electrode group includes another portion of the plurality of electrodes.

What is claimed is: 
     
         1 . A fingerprint sensor comprising:
 a panel comprising a sensor array comprising first electrodes extended in a first direction and second electrodes extended in a second direction intersecting with the first direction; and   a forged fingerprint analyzer configured to provide signals having different frequencies to a first electrode group and a second electrode group, and to measure an impedance between the first electrode group and the second electrode group to determine whether a fingerprint applied to the sensor array is forged,   wherein the first electrode group comprises a portion of a plurality of electrodes among the first electrodes or the second electrodes, and the second electrode group comprises another portion of the plurality of electrodes.   
     
     
         2 . The fingerprint sensor of  claim 1 , wherein the first electrode group and the second electrode group are spaced apart from each other with an electrode among the plurality of electrodes disposed between the first electrode group and the second electrode group, and the electrode among the plurality of electrodes is floated. 
     
     
         3 . The fingerprint sensor of  claim 2 , wherein some electrodes included in the first electrode group and the second electrode group are continuously disposed adjacent to each other. 
     
     
         4 . The fingerprint sensor of  claim 1 , wherein the forged fingerprint analyzer comprises a frequency signal provider configured to provide a high frequency signal, a low frequency signal, and a reference signal to the first electrode group and the second electrode group. 
     
     
         5 . The fingerprint sensor of  claim 4 , wherein:
 the frequency signal provider is configured to provide the high frequency signal to the first electrode group, and to provide the reference signal to the second electrode group, at a first point in time; and   the frequency signal provider is configured to provide the low frequency signal to the first electrode group, and to provide the reference signal to the second electrode group, at a next point in time after the first point in time.   
     
     
         6 . The fingerprint sensor of  claim 5 , wherein the forged fingerprint analyzer further comprises an impedance measurer configured to measure the impedance between the first electrode group and the second electrode group at the first point in time and the next point in time. 
     
     
         7 . The fingerprint sensor of  claim 6 , wherein the forged fingerprint analyzer further comprises a forged fingerprint determiner configured to determine whether the fingerprint is forged by comparing the impedance measured at the first point in time and the impedance measured at the next point in time with each other. 
     
     
         8 . The fingerprint sensor of  claim 7 , wherein the forged fingerprint analyzer is configured to determine that the fingerprint is forged, in response to a difference between the impedance measured at the first point in time and the impedance measured at the next point in time being slight. 
     
     
         9 . The fingerprint sensor of  claim 1 , further comprising a fingerprint sensing circuit module configured to:
 apply driving signals to the first electrodes; and   detect, from the second electrodes, capacitances generated between the first electrodes and the second electrodes to sense the fingerprint.   
     
     
         10 . A fingerprint sensor comprising:
 a panel comprising
 a sensor array comprising first electrodes and second electrodes disposed above the first electrodes, and 
 an auxiliary electrode unit comprising auxiliary electrodes disposed adjacent to the sensor array; 
   a fingerprint sensing circuit module configured to sense a fingerprint from capacitances generated between the first electrodes and the second electrodes; and   a forged fingerprint analyzer configured to provide signals having different frequencies to the auxiliary electrodes, and to determine whether the fingerprint is forged based on an impedance between the auxiliary electrodes.   
     
     
         11 . The fingerprint sensor of  claim 10 , wherein:
 the forged fingerprint analyzer is configured to provide a high frequency signal to one or more electrodes among the auxiliary electrodes; and   the fingerprint sensing circuit module is configured to determine whether the fingerprint is forged based on capacitances formed between the second electrodes and one or more electrodes among the auxiliary electrodes.   
     
     
         12 . The fingerprint sensor of  claim 11 , wherein the fingerprint sensing circuit module is further configured to determine that the fingerprint is forged, in response to an increase in the capacitances formed between the second electrodes and the one or more electrodes among the auxiliary electrodes. 
     
     
         13 . The fingerprint sensor of  claim 10 , wherein the fingerprint sensing circuit module is further configured to detect whether the fingerprint is forged based on whether a distance is present between an edge region of the sensor array and a contact object disposed on the sensor array. 
     
     
         14 . The fingerprint sensor of  claim 10 , wherein the panel further comprises a conductive layer formed on the auxiliary electrodes. 
     
     
         15 . The fingerprint sensor of  claim 10 , wherein the sensor array is disposed in a central region of a home button configured to provide a physical input to an electronic apparatus, and the auxiliary electrodes are formed by a metal ring comprising two parts formed on an outer side of the home button. 
     
     
         16 . The fingerprint sensor of  claim 10 , wherein the sensor array is disposed in a central region of a home button configured to provide a physical input to an electronic apparatus, and the auxiliary electrodes are disposed in outer regions of the home button surrounding the central region of the home button. 
     
     
         17 . The fingerprint sensor of  claim 10 , wherein the panel is formed in one or both of a display region and a bezel region of an electronic apparatus. 
     
     
         18 . The fingerprint sensor of  claim 10 , wherein each of the auxiliary electrodes is spaced apart from the sensor array by a distance of 3 μm or less. 
     
     
         19 . A fingerprint sensing apparatus, comprising:
 a frequency signal provider configured to provide signals having different frequencies to a sensor array comprising first electrodes extended in a first direction and second electrodes extended in a second direction;   an impedance measurer configured to measure an impedance between a first electrode group and a second electrode group, wherein the first electrode group and the second electrode group each include electrodes among the first electrodes, or each include electrodes among the second electrodes;   a fingerprint forgery determiner configured to determine whether a fingerprint applied to the sensor array is forged based on the measured impedance; and   a sensing circuit module configured to
 apply driving signals to the first electrodes, and 
 detect, from the second electrodes, capacitances generated between the first electrodes and the second electrodes to sense the fingerprint. 
   
     
     
         20 . The fingerprint sensing apparatus of  claim 19 , wherein:
 the providing of the signals having different frequencies to the sensor array comprises
 providing a first signal having a first frequency to the first electrode group, and providing a reference signal to the second electrode group, at a first point in time, 
 providing a second signal having a second frequency to the first electrode group, and providing the reference signal to the second electrode group, at a next point in time after the first point in time; and 
   the measuring of the impedance between the first electrode group and the second electrode group comprises measuring the impendence between the first electrode group and the second electrode group at the first point in time and the next point in time.   
     
     
         21 . The fingerprint sensing apparatus of  claim 20 , wherein the fingerprint forgery determiner is configured to determine that the fingerprint is forged, in response to a difference between the impedance measured at the first point in time and the impedance measured at the next point in time being slight. 
     
     
         22 . The fingerprint sensing apparatus of  claim 19 , wherein the first electrode group and the second electrode group are spaced apart from each other by a floated electrode. 
     
     
         23 . An electronic apparatus comprising:
 a button configured to provide a physical input to the electronic apparatus, wherein the button comprises
 a sensor array disposed in a central region of the button, and comprising first electrodes and second electrodes, and 
   auxiliary electrodes disposed in the button in one or both of an outer region of the button surrounding the sensor array and a metal ring formed at an outer circumference of the button; a fingerprint sensing circuit module configured to sense a fingerprint from capacitances generated between the first electrodes and the second electrodes by a contact object disposed on the sensor array; and   a forged fingerprint analyzer configured to determine whether the fingerprint is forged based on capacitances formed between the second electrodes and an electrode among the auxiliary electrodes.   
     
     
         24 . The electronic apparatus of  claim 23 , wherein each of the auxiliary electrodes is spaced apart from the sensor array by a distance less than 3 μm. 
     
     
         25 . The electronic apparatus of  claim 23 , wherein the forged fingerprint analyzer is further configured to:
 provide signals having different frequencies to the auxiliary electrodes; and   determine whether the fingerprint is forged based on an impedance between the auxiliary electrodes.   
     
     
         26 . The electronic apparatus of  claim 23 , wherein the fingerprint sensing circuit module is further configured to detect whether the fingerprint is forged based on whether a distance is present between an edge region of the sensor array and the contact object.